Modeling a fish with curves - complication at tail
Why not give sculpting a try? You could make something close to what you want and touch up the details in sculpt...

heres a link to a video instructing how to use dynamic topology (and by extension sculpt mode)

https://www.youtube.com/watch?v=opsKPCCFbr4

docs on sculpting

http://wiki.blender.org/index.php/Doc:2.6/Manual/Modeling/Meshes/Editing/Sculpt_Mode



docs on dynamic topology 

(note that this feature has been changed in 2.7, it can now be found under the header labelled "dynotopo")

http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66/Dynamic_Topology_Sculpting